A damper unit, a damper assembly, and a method for making a damper unit

ABSTRACT

A damper unit for use in a vibration-reducing assembly for a steering wheel is disclosed. The damper unit includes a slider configured, upon horn activation, to slide on a guide shaft. A damper element made from an elastomeric material is arranged on a first part of the slider. A molded horn spring element is molded directly on a second part of the slider and is configured to exert a spring force on the slider. The damper unit provides a unitary structure providing both a vibration damping function and a horn spring function in one single assembly unit, reducing the number of components to assemble. A vibration-reducing damper assembly including one or more such damper units is also disclosed, as well as a method of making such a damper unit.

TECHNICAL FIELD

The present disclosure generally relates to the field of frequency-tuneddampers for motor vehicles. A damper unit for use in avibration-reducing assembly for a steering wheel is disclosed. Avibration-reducing damper assembly including one or more such damperunits is also disclosed, as well as a method of making such a damperunit.

BACKGROUND

The function of frequency-tuned vibration dampers, also termed tunedmass dampers, dynamic dampers or vibration absorbers, is based on adampened spring-mass system which counteracts and reduces vibrations ina structure or surface to which the damper is connected by using one ormore elastic damper elements for transferring vibrations from avibrating structure to at least one mass which is caused to vibrate outof phase such as to dampen the vibrations. WO 01/92752 A1, WO2013/167524 A1, and WO 2008/127157 A1 disclose examples offrequency-tuned vibration dampers.

In the automotive industry, some steering wheels are provided withfrequency-tuned vibration dampers for reducing steering wheel vibrationscaused by vibrations from the road and engine being transferred to thesteering wheel. In such damper structures, the weight of an airbagmodule may be used as part of the weight of the mass in the spring-masssystem. Also, steering wheels are generally provided with a hornactivation mechanism by which a driver may activate a horn of thevehicle. Horn activation mechanisms of mechanical type typicallycomprise one or more metal spiral springs, referred to as horn springs,for returning the horn activation mechanism to its normal state after ahorn activation. Electronic horn activation mechanisms without hornsprings are also available.

EP 2 085 290 discloses an example of a prior art vibration-reducingdamper structure for a steering wheel, including an elastic damperelement arranged on a slider which is slidably mounted on a bolt shaft.Vibrations in the steering wheel are transferred by the elastic damperelement to the airbag assembly for dampening purposes. During hornactivation, the slider may slide along the bolt shaft. A conventionalspiral spring is placed on the bolt shaft and is compressed upon hornactivation for bringing the slider back to its normal position when thehorn activation is terminated. One drawback of this prior art is that isthat the assembly of the overall structure is complicated and timeconsuming, increasing manufacturing time and cost.

U.S. Pat. No. 8,985,623 B2 discloses an alternative damper structure fora steering wheel. The overall operation is similar to the one indisclosed in EP 2 085 290 mentioned above, but the elastic element isencapsulated in a rigid multi-part protector structure. The protector isslidably arranged on a shaft and is biased by a horn spring towards thenon-activated position of the horn activation mechanism. This prior-artsolution has essentially the same drawbacks, and actually requiresadditional cost and time for manufacturing the protector.

SUMMARY OF INVENTION

In the light of the above, it is an object of the present inventiveconcept to address the above-mentioned disadvantages of the prior artand, to this end, provide (i) a damper unit for use in avibration-reducing assembly for a steering wheel, (ii) avibration-reducing assembly for dampening vibrations in a steeringwheel, and (iii) a method for manufacturing such a damper unit.

According to a first aspect of the inventive concept, there is provideda damper unit for use in a vibration-reducing assembly for a steeringwheel, said damper unit comprising:

-   -   a slider having a central bore extending along an axis, said        slider being configured, upon horn activation on the steering        wheel, to slide in the direction of said axis on a guide shaft        received in said bore;    -   a damper element which is made from an elastomeric material and        is arranged on a first part of the slider; and

a molded horn spring element which made from an elastomeric material andcomprises a horn spring part and an attachment part molded in one piecewith each other, wherein the attachment part of the horn spring elementis molded on a second part of the slider, and wherein the horn springpart is configured to exert a force on the slider in the direction ofthe axis before and upon horn activation on the steering wheel.

According to a second aspect of the inventive concept, there is provideda vibration-reducing assembly for dampening vibrations in a steeringwheel, said assembly comprising:

-   -   a base structure which is fixed to the steering wheel and        presents vibrations to be dampened;    -   a guide shaft fixed to the base structure;    -   a damper unit as claimed in any of claims 1 to 8, wherein the        guide shaft is slidably received in the central bore of the        slider, and wherein the horn spring part of the damper unit is        configured, upon horn activation on the steering wheel, to be        compressed in response to the slider moving along the axis of        the damper unit towards the base structure; and    -   a mass which is supported by the base structure via the damper        element of the damper unit for allowing movement of the mass        perpendicular to said axis;    -   wherein the damper element of the damper unit is configured to        transfer vibrations, directed perpendicular to said axis, from        the steering wheel to the mass; and

wherein the damper element and the mass are configured to operate as aspring-mass system forming a frequency-tuned dynamic damper fordampening said vibrations in the base structure and the steering wheel.

According to a third aspect of the inventive concept, there is provideda method for making a damper unit, comprising:

-   -   providing a slider having a central bore extending along an axis        of the damper unit;    -   providing a damper element which is made from an elastomeric        material on a first part of the slider;

molding a horn spring element from an elastomeric material, said moldedhorn spring element comprising a horn spring part and an attachment partmolded in one piece with each other, wherein the attachment part ismolded on a second part of the slider.

The inventive concept presents at least the following advantages overthe prior-art:

-   -   A main advantage obtained by the inventive concept is that the        number of components to manufacture, manage and assemble is        reduced by using the inventive damper unit. During assembly, the        inventive damper unit is already provided with the molded horn        spring element. Thereby, no separate spiral horn spring has to        be handled during assembly since the horn spring is already in        place as an integral component of the damper unit. The horn        spring mechanism is directly and automatically obtained upon        mounting the slider on the guide shaft.    -   In preferred embodiments, the elastomeric damper element is also        already provided on the damper unit when the unit is to be        mounted in the assembly.    -   The horn plate can be quickly and easily connected to the base        structure by one or more damper units, wherein each damper unit        automatically provides—as a direct result of mounting the        unit—both a vibration dampening function and a horn spring        function without any need of handling or assembling a separate        damping element or a separate horn spring.    -   In embodiments where also the damper element is molded on the        slider, it is possible to manufacture a multi-function unitary        damper unit by molding the damper element and the horn spring        element in one piece with each other on the slider in one single        molding step. The unitary damper unit—including slider plus        damper element plus horn spring—will present a slider function,        a vibration damping function and a horn spring function    -   By molding the elastomeric horn spring element on the slider, it        is possible to both manufacture the horn spring and to bond the        horn spring to the slider in one single molding operation.    -   By molding the horn spring element on the slider, the quality of        the final product may be increased since no separate alignment        and mounting of the horn spring is needed.    -   By using a damper unit according to the inventive concept it is        possible to perform the assembly essentially from one side only        of the horn plate, compared to prior art solutions where the        slider is inserted from one side of the horn plate and the        damper element and locking means are assembled from the opposite        side of the horn plate.    -   The above and further advantages will become apparent from the        following disclosure.

Preferred embodiments of the inventive concept are set out in thedependent claims.

The molded horn spring part is configured to exert a force on the sliderin the direction of the axis before and upon horn activation on thesteering wheel. When the damper unit is installed in the assembly, themolded horn spring part is pre-compressed, such that it is configured toexert a biasing force on the slider in the non-activated state also ofthe horn activation mechanism. Upon horn activation, the horn springpart is further compressed. The reason for installing the horn springpart in a biased state is to ensure that a fully developed horn springforce is available essentially immediately upon horn activation by thedriver.

In preferred embodiments, the horn spring element may be bonded to theslider. This has the advantage that a ready-to-assemble damper unit isprovided in which the horn spring element molded on the slider is bondedto the slider and thus held in correct position on the slider when thedamper unit is mounted in the vibration-reducing assembly. Differentbonding techniques may be used, individually or in combination. Onebonding technique includes frictional bonding. A frictional bonding mayin some embodiments be obtained as a result of a post-molding shrinkingof the elastomeric material around the slider.

In some embodiments, the attachment part of the horn spring element maybe mechanically bonded to the slider (although frictional bonding mayalso be considered a mechanical bonding). In order to establish such amechanical bonding, the attachment part of the horn spring element maybe mechanically bonded to the slider by means of one or more moldedlocking elements. The molded locking elements may be molded in one piecewith the horn spring element. The molded locking elements may be inmechanical locking engagement with associated one or more structures ofthe slider, such as locking openings in the slider.

In some embodiments, the attachment part of the horn spring element maybe chemically bonded to the slider, such as by adhesion (e.g. by usingadditives and/or primers) or other reaction.

In some embodiments, the attachment part of the horn spring element maybe both mechanically bonded and chemically bonded to the slider.

In the present disclosure, when an elastomeric element is stated to be“molded on the slider” is should be interpreted as the relevant elementis first of all a molded detail being manufactured by molding. Second,the expression “molded on the slider” is to be interpreted as therelevant element is created/molded directly on the slider, in contrastto prior-art solutions where the relevant element is made as a separatepart, such as in the form of a conventional spiral-shaped metal springmade separately from the slider and which mounted in the assembly as aseparate part. In preferred embodiments, the elastomeric materialincludes silicone rubber.

In the present disclosure, the terms “bonding” or “bonded” are to beinterpreted as a connection or attachment between the relevant elementand the slider preventing the element from falling off from or beingeasily removed from the slider. The term “bonding” is thus to beinterpreted as an attachment or connection ensuring that the relevantelement, as an integral part of the damper unit from an assemblyperspective, is being held by the bond in its intended position on theslider. In embodiments where an element can easily be removed from theslider or easily fall of from the slider, such as a cylindrical damperelement having a central bore in which a guide shaft is received withoutany mechanical bonding or adhesion acting in the axial direction, theelement is not considered to be “bonded” to the slider although radialmovement relative to the slider may be restricted.

In the present disclosure, “mechanically bonded” or “mechanical bonding”is to be interpreted as an alternative to “chemical bonding”.Mechanically bonding should be interpreted as a non-chemical attachmentof the relevant element to the slider, ensuring that the relevantelement is mechanically maintained in its intended position on theslider.

In the present disclosure, expressions as “chemically bonded”, “chemicalbonding”, “adhesion” binding or “adhesion” and the like should beinterpreted as an alternative to mechanical bonding. Chemical bonding isconsidered a bonding between molecules. In some embodiments, mechanicaland chemical bonding may be used in combination. A preferred chemicalbonding may be adhesion bonding rather than glue. Chemical bonding maybe provided during molding. In some embodiments, chemical bonding may beobtained by using an overmolding technique with adhesion bonding betweensimilar or related polymers.

In a preferred embodiment of obtaining a mechanical bonding of the hornspring element to the slider, one or more locking elements may be moldedin one piece with not only the horn spring element, but with theelastomeric damper element also. Thereby, the elastomeric damperelement, the elastomeric horn spring element, and said one or morelocking elements are molded in one piece with each other on the slider,forming a unitary molded body mechanically bonded to the slider, andpreferably also chemically bonded to the slider. Locking openings in theslider may be formed as through-holes in a radially extending flange onthe slider, wherein the damper element and the horn spring element maybe arranged on axially opposite sides of the flange, and wherein thelocking elements form molded “bridges” between the damper element andthe horn spring element, extending through the openings in the flange.

In some embodiments, the slider may comprise a tubular part and aradially extending flange but with no locking openings. A radiallyextending flange may be in engagement with the attachment part of themolded horn spring element and may give support for spring forces fromthe horn spring part. A radially extending flange may also be used forgiving axial support for the elastomeric damper element on the oppositeside of the flange. In preferred embodiments, one single flange may beused for both purposes, although it would be possible to use twoflanges. Other designs of protruding elements than a flange are alsopossible.

In some embodiments, the slider comprises a tubular element and aradially flange which divides the tubular slider element into a firstand a second tubular part, wherein the damper element may be arranged onthe first tubular part and the horn spring element may be provided onthe second tubular part. The attachment part of the horn spring elementmay be bonded to the flange and/or the second tubular part. The hornspring part of the horn spring element may in some embodiments extend atleast in part axially beyond the end of the second tubular part, inorder to allow compression of the horn spring part upon horn activation.In other embodiments, the second tubular part may be dispensed with andthe attachment part may be bonded directly to the flange, for instanceby locking elements as described above.

In some embodiments, the molded horn spring part is at least partlybellow-shaped in order to provide the aimed-at horn spring function. Inother embodiments, other horn spring designs may be possible, forinstance designs relying at least partly on compression rather thanflexing of the elastomeric material.

In preferred embodiments, not only the horn spring part is molded on theslider but also the damper element is molded on the slider, wherein thedamper element may optionally be mechanically and/or chemically bondedto the slider. In such embodiments, the horn spring and the damperelement are preferably molded in one piece with each other.

As known as such in the prior art, the weight of an airbag assembly inthe steering wheel may be preferably be used as part of the mass for thedynamic damping function of the dynamic spring-mass system in order touse a separate dead weight for this purpose. The weight of the hornplate and of further components supported by the horn plate will alsocontribute to the total weight of the vibrating mass.

In some embodiments of the inventive vibration-reducing assembly, theelastomeric damper element of the damper unit is received in a mountingopening of the horn plate, wherein the damper element presents an outerengagement surface, which is in engagement with an inner engagementsurface of a mounting opening of the horn plate for transferring thevibrations. The inner engagement surface may be formed by a sleeveextending from the horn plate for providing an axially extendedengagement interface. Such a sleeve may be a sleeve molded on the hornplate. Different designs of the engagement surfaces will be disclosedbelow.

The inventive vibration-reducing damper assembly comprises at least one,but preferably a plurality of damper units according to the invention.Optionally the damper units may be configured to dampen vibrations indifferent directions.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept, some non-limiting preferred embodiments, andfurther advantages of the inventive concept will now be described withreference to the drawings in which:

FIG. 1A illustrates a steering wheel of a vehicle.

FIG. 1B illustrates main parts of a vibration-reducing assembly.

FIG. 2 is an exploded view of a vibration-reducing assembly.

FIGS. 3 and 4 are sectional views of the assembly in FIG. 1B.

FIG. 5 is a side view of the assembly in FIG. 1B.

FIGS. 6 and 7 illustrate in larger scale a damper unit mounted in theassembly in FIG. 2.

FIGS. 8A to 8D illustrate a slider of a 1^(st) embodiment of a damperunit.

FIGS. 9A to 9E illustrate a 1^(st) embodiment of a damper unit.

FIGS. 10A and 10B illustrate a unitary elastomeric body of the damperunit according to the 1^(st) embodiment.

FIGS. 11A and 11B illustrate a 2^(nd) embodiment of a damper unit.

FIGS. 12A and 12B illustrate a 3^(rd) embodiment of a damper unit.

FIGS. 13A to 13D illustrate a slider of a 4^(th) embodiment of a damperunit.

FIGS. 14A to 14C illustrate a unitary elastomeric body of the damperunit according to the 4^(th) embodiment.

FIGS. 15A to 15C illustrate the damper unit according to the 4^(th)embodiment.

FIGS. 16A to 16F illustrate an assembly method using the damper unitaccording to the 4^(th) embodiment.

FIGS. 17A to 17C illustrate a horn activation of an assembly includingdamper units according to the 4^(th) embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present inventive concept relates in general to the field offrequency-tuned vibration dampers, also referred to as dynamic dampers.Such dampers may be used to dampen vibrations in a vibrating surface orstructure, such as a vibrating component like a steering wheel of amotor vehicle. A dynamic vibration damper comprises a mass acting as avibration body, and at least one elastic damper element. The mass andthe least one elastic damper element together provide a dampenedspring-mass system, and may be connected to the vibrating structure,optionally by means of an intermediary component.

The weight of the mass, and the stiffness and damping of the elasticdamping element are selected to provide a damping effect on thevibrating structure, which can be expected to vibrate at one or morepredetermined target frequencies. When the vibrating structure vibratesat a target frequency, the mass is caused to oscillate/resonate at thesame frequency as the structure but out of phase, such that thevibration of the structure is substantially dampened. The mass mayvibrate with an amplitude substantially greater than the vibrationamplitude of the vibrating structure.

The present inventive concept relates to a damper unit for use in such adynamic damper assembly arranged in a steering wheel of a vehicle fordampening steering wheel vibrations.

1^(st) Embodiment

FIG. 1A illustrates a steering wheel 2 in a motor vehicle 4. Vibrationsfrom the road and the engine may be transferred to the steering wheel 2.These steering wheel vibrations may be perpendicular to the steeringcolumn, as indicated by up-down and left-right arrows. The steeringwheel 2 is provided with a vibration-reducing assembly 6, which isschematically indicated by a dashed box inside the steering wheel 2 andwhich is configured to dynamically dampen at least some of the steeringwheel vibrations.

As known in the art, the steering wheel 2 is also provided with a hornactivation mechanism for activating a horn (not shown) of the vehicle 4.To this end, a horn activation pad 8 is arranged in the center of thesteering wheel 2 to be pressed by the driver upon horn activation. Whenthe driver releases the horn activation pad 8, the horn activationmechanism returns to its non-activated or initial state by means of oneor more horn springs. In the illustrated embodiment, the horn activationmechanism is of mechanical type. There exist horn activation mechanismsof electronic design also, not including horn springs.

Furthermore, an airbag assembly may be arranged inside the steeringwheel 2 under the horn activation pad 8. FIG. 1B schematically shows apart 10 of a gas generator of an airbag assembly. In the presentembodiment, the weight of the airbag assembly is used as at least partof the total weight of the mass used in the vibration-reducingspring-mass system. Thereby, the use of separate deadweights for thispurpose may be avoided or substantially reduced.

The vibration-reducing assembly 6 inside the steering wheel 2 isarranged on and supported by a base structure or armature 12 fixed tothe steering wheel 2. The vibrations in the steering wheel 2 are thuspresent in the base structure 12 also, as indicated by vibrations V inFIG. 7 perpendicular to the steering column. The vibration-reducingassembly 6 comprises a horn plate 14 on which the airbag assembly ismounted, including the gas generator and the airbag. In a preferredembodiment, the horn plate 14 is made of metal and is optionallyprovided with a plastic cover made of a relatively rigid plasticmaterial molded on the horn plate 14, including a top cover 16 and abottom cover 18. The horn plate 14 is provided with three openings, eacharranged to receive part of a damper unit 40 as will be described below.In the illustrated embodiment, a cylindrical sleeve 20 is arrangedaround each opening in the horn plate 14 and extends above the plane ofthe horn plate 14. The sleeves 20 may by molded in one piece with theplastic cover 16, 18, thus being rigidly connected to the horn plate 14.In other embodiments, the sleeves 20 may be dispensed with.

As shown in FIG. 2, the base structure 12 may comprise three supportprojections 13, projecting towards the horn plate 14 and each providedwith a threaded bolt hole. A separate bracket 22 is supported on thesupport projections 13. The bracket 22 has a through opening 24 alignedwith each support projection 13. Around each through opening 24, thebracket 22 presents a horn spring support surface 26 facing the hornplate 14, and on the opposite side a bracket support surface 28 facingthe base support 12. In the assembled state (FIG. 7), the bracket 22 issupported at the bracket support surfaces 28 by the support projections13.

The bracket 22 is a multi-function bracket for supporting variouscomponents, and may especially comprise parts of the horn switchmechanism of the steering wheel 2, here in the form of four contactstuds 30 which project towards the horn plate 14 and are aligned withcorresponding contact pads 15 protruding from the bottom side of thehorn plate 14. As shown in FIG. 5, the contact studs 30 and the contactpads 15 are normally located at a distance D from each other. Upon hornactivation, the horn plate 14 is pressed towards the bracket 22 untilthe contact pads 15 and the contact studs 30 are brought into electricalengagement for activating the horn, and at the same time a movement stopfor the horn plate 14. As an illustrative example, the distance D may bein the order of a few millimeters.

The horn plate 14 with the airbag assembly fixed thereto is movablysupported on the base structure 12 via three damper units 40. It may benoted that although this unit is termed “damper unit” in thisdisclosure, a damper unit 40 provides both a vibration damping functionand a separate horn spring function as will be described below. Eachdamper unit 14 is configured to allow the mass represented at least bythe horn plate 14 and the airbag assembly to move (i) perpendicular tothe axis A of the damper unit 40 for vibration damping purposes, and(ii) along the main axis A for horn activation purposes. A 1stembodiment of a damper unit 40 will now be described with reference toFIGS. 8A to 8D, FIGS. 9A to 9D, and FIGS. 10A and 10B.

The damper unit 40 comprises a slider 50, a damper element 70 and a hornspring element 90. In a preferred embodiment, the slider 50, the damperelement 70 and the spring element 90 may be bonded together into oneunit 40, such that these three components form a unitary structure readyto be connected to the base structure 12 and the horn plate 14. Thecomponents 50, 70 and 90 may be mechanically and/or chemically bondedtogether, in the sense that they cannot easily be taken apart from eachother.

FIGS. 8A to 8D illustrate a 1^(st) embodiment of the slider 50. Theslider 50 may be made from a relatively rigid material, such as asuitable synthetic resin material. In horn activation structures of themechanical type, the slider is arranged to slide on a guide shaft uponhorn activation as will be described below. The slider 50 comprises atubular element 52 defining a through bore 54 for receiving the guideshaft, and a radially extending flange 56. The flange 56 divides thetubular element 52 into a first tubular part 58 on one side of theflange 56, and a second tubular part 60 on the axially opposite side ofthe flange 56. In the illustrated embodiment, the first tubular part 58is longer than the second tubular part 60. The flange 56 presents one ormore locking openings here in the form of a plurality of axiallyoriented through holes 62 used for mechanically bonding the damperelement 40 and the horn spring element 90 together and to the slider 50.The flange 56 also serves to take up spring forces from the horn springelement 90, and to transfer axial forces between the slider 50 and thedamper element 70.

Reference is now made to FIG. 9A to 9E illustrating a 1^(st) embodimentcomplete damper unit 40. The elastic damper element 70 is arranged onthe first slider part 58. The elastic damper element 70 is made of anelastomeric material, such as silicone rubber, suitable for use as theelastic spring element in a dynamic damper. The damper element 70 isconfigured to operate together with the mass represented by at least theairbag module and the horn plate 14 as a spring-mass system forming afrequency-tuned dynamic vibration damper for dampening the vibrations Vin the base structure 12 and the steering wheel 2.

In the illustrated embodiment, the damper element 70 has a generalcylindrical shape with a distal end 71 facing away from the flange 56, aproximal end 72 facing towards the flange 56, and an outer engagementsurface 75. As an illustrative, but non-limiting example the axiallength of the damper element can be in the order of 7 mm. In the finalvibration-reducing assembly as shown in FIG. 7, the outer engagementsurface 75 of each damper element 70 is in engagement with an innerengagement surface 21 of an associated sleeve 20 on the horn plate 14for transferring vibrations to the horn plate 14. In the illustratedembodiment, the axial length of the damper element 70 correspondsessentially to the axial length of the first slider part 58 but extendsaxially a short distance beyond the distal end of the first slider part58. The proximal end 72 of the damper element 70 is in contact with theflange 56. The distal end 71 of the damper element 70 has an increasedouter diameter for forming a ring-shaped radial extension 73. Theproximal end 72 of the damper element 70 has an even larger diameter andis arranged to extend under the horn plate 14 in the assembly 6. Theproximal end 72 may present an upwardly directed support ring 74 definedby a ring-shaped groove 76 for reasons that will be explained below.

In the illustrated 1^(st) embodiment, the damper element 70 is dividedinto a plurality of axially extending ribs 77 (FIG. 9D), which arecircumferentially distributed about the axis A of the damper unit 40 andwhich define spaces 78 there between. The radially outer surfaces of theribs 77 together form the outer engagement surface 75 of the damperelement 70. The operation and advantages obtained by the ribs 77 and thespaces 78 will be explained below. In other embodiments, the damperelement 40 may have the form of a circumferentially unbroken cylinderdefining a continuous outer engagement surface.

The horn spring element 90 of the damper unit 40 is arranged on a secondpart of the slider 50, in this embodiment on the axially opposite sideof the flange 56 on the second tubular part 60 and also on part of theflange 56. The horn spring element 90 is made from an elastomericmaterial and comprises a horn spring part 94 and an attachment part 92(FIG. 9C), which are molded from an elastomeric material in one piecewith each other. During molding of the horn spring element 90, at leastthe attachment part 92 thereof is molded on the slider 50 such that thehorn spring element 90 is correctly positioned on the slider 50 whenbeing manufactured.

As best shown in FIG. 9C, the attachment part 92 of the horn springelement 90 has an L-shaped cross section with one leg in contact withthe shorter tubular part 60 of the slider 50 and one leg in contact withthe flange 56. In other embodiments, the shorter tubular part 60 isdispensed with and the attachment part 92 may engage the flange 56 only.

The elastomeric material used for the horn spring element 90 may be anyelastomeric material suitable to provide the aimed-at horn springfunction, depending on the required spring constant. In a preferredembodiment, the material comprises silicone rubber. The same elastomericmaterial may be used for molding the damper element 40 and the hornspring element 90, especially if these elements are molded in one piecewith each other. In the illustrated first embodiment, the horn springpart 94 is bellow-shaped in order to provide the spring action in thedirection of the axis A. Other embodiments may have a different springdesign, relying in part or only on compression rather than flexing as inthe bellow-shaped design. The spring constant may be varied by varyingone or more parameters of the horn spring part 94, such as the material,the axial length, the diameter, the wall thickness, and thebellow-design (angles, etc.). It may also be possible to use a “broken”design presenting openings and/or separate spring legs, which also wouldpresent further tuning options for the spring characteristics.

In the final vibration-reducing assembly 6, the molded horn spring part94 is configured to act as a horn spring in the direction of the axis A,to exert a spring force on the horn plate 14 via the slider 50 and thedamper element 40. The spring force will be present for returning thehorn plate 14 when the horn activation is terminated. Due to thepre-compression of the horn spring part 94, the spring force is presentas a biasing spring force in the non-activated state also. An advantageobtained thereby, is that the spring force generated by the horn springis essentially immediately available as soon as the driver operates thehorn.

In the illustrated first embodiment, the horn spring element 90 ismolded directly on the slider 50, avoiding the need to manufacture ametal spiral spring separately, and to attach and/or align such aseparate metal spiral spring in relation to the slider during theassembly. At present, overmolding is considered a preferred moldingmethod, but other techniques may also be considered, such as 2Kinjection molding where both the slider 50 and the elastomericcomponents are manufactured using one single 2K injection moldingmachine. Although not presently preferred, different molding techniquesmay be used for the damper element 70 and the horn spring element 90. Inpreferred embodiments, the horn spring element 90 is not only molded onthe slider 50 but is also bonded to the slider 50. The bonding may bemechanical (including frictional bonding) and/or chemical.

In the illustrated 1^(st) embodiment, the horn spring element 90 ismechanically bonded to the slider 50 to keep the horn spring element 90in the illustrated position on the slider 50. This is achieved by aplurality of locking elements 100, which are molded in one piece withthe horn spring element 90 and which are in locking engagement with thelocking openings 62 in the flange 56. In the illustrated embodiment, thedamper element 40 also is mechanically bonded to the slider 50 to keepthe damper element 40 in the illustrated position on the slider 50. Thisis also achieved by the locking elements 100. In the preferredembodiment, the same locking elements 100 are used for bonding both thehorn spring element 90 and the damper element 40, such that theelastomeric horn spring element 90, the elastomeric damper element 40and the locking elements 100 are molded together as one unitary body,mechanically bonded to the slider 50 by the through openings 62. Forexplanatory purposes only, this unitary elastomeric body 70, 90, 100 isshown without the slider 50 in FIGS. 10A and 10B. In this embodiment,there may also be a frictional bonding between the elastomeric elements70, 90 and the tubular parts of the slider 50.

In some embodiments, one or both of the damper element 40 and the hornspring element 90 may be chemically bonded to the slider 50 by adhesion.It is also possible to use both mechanical bonding as disclosed in thedrawings, and chemical adhesion, for one or both of the damper element40 and the horn spring element 90. The chemical adhesion may beimplemented during molding. It is also possible to rely on frictionalbonding, only or in part. Frictional bonding may be obtained by apost-molding shrinking of the elastomeric material.

A method for assembling the vibration-reducing assembly 6 using a numberof damper units 40 according to the 1^(st) embodiment will now bedescribed with reference to FIGS. 2 to 7. The sequence or order of stepsas described here may be varied. As a first step, the bracket 22 may beplaced upon the projections 13 of the base structure 12. As a secondstep, the slider 50 and the ribbed-shaped damper element 70 of eachdamper unit 40 may be inserted from below in FIG. 2 into an associatedopening of the horn plate 14.

It should be noted that slider 50 and the elastomeric damper element 70of each damper unit 40 are inserted together and from one side only ofthe horn plate 14. During insertion of the damper element 70, theradially outer engagement surface 75 of the damper element 70 is broughtinto engagement with the inner engagement surface 21 of thecorresponding sleeve 20, such that steering wheel vibrations V may betransferred from the damper element 70 to the horn plate 14. Preferably,the radial dimensions are selected such that the damper element 70 issomewhat radially compressed between the slider 50 and the innerengagement surface 21 of the sleeve 20.

During the insertion of the damper element 70, the support ring 74integrally formed with the damper element 70 will engage the bottom sideof the horn plate 14 as shown in FIG. 7, defining the final insertionposition. During the insertion of the damper element 70, the upperradial extension 73 of the damper element 70 will be temporarilycompressed in order to pass the sleeve 20. In the final position, theextension 73 will extend over the upper edge of the sleeve 20. Thereby,the support ring 74 and the radial extension 73 will together ensurethat the damper element 70 is held correctly axially positioned/lockedin relation to the horn plate 14. No separate locking elements areneeded, and the axial locking is automatically obtained during theone-sided insertion of the damper unit. It will also be noted that anaxial distal part of the elastomeric damper element 70 in this 1^(st)embodiment will extend axially beyond the distal edge of the sleeve 20.

When the damper elements 70 have been correctly positioned in the hornplate 14, a bolt 120 may be inserted into the bore 54 of each slider 50.Each bolt 120 has a bolt head 126, a cylindrical guide shaft 122 and athreaded end 124. The tubular part 52 of the slider 50 may slide alongthe guide shaft 122. As shown in FIG. 7, the bolts 120 are secured inthe bolt holes of the extensions 13 of the base structure 12. During thefinal fastening of each bolt 120, a pre-compression of the correspondinghorn spring part 94 is obtained. As a non-limiting example, a hornspring part may be pre-compressed from 10 mm to 7 mm during assembly andthen further compressed one or a few mm upon horn activation. In thefinal assembly, the distal end 95 of each horn spring part 94 engagesthe associated horn spring support surface 26 of the bracket 22. In thefinal assembled state, the bolt head 126 is in axially engagement withthe upper end 71 of the elastomeric damper element 70, with the radialextension 73 projecting between the sleeve 20 and the bolt head 126.

It will be understood that the disclosed method of making the damperunit 40 and assembling a vibration-reducing assembly using the inventivedamper units 40 may provide substantial advantages in terms ofmanufacturing cost and time, but also in terms of quality. Compared withthe prior art where a number of individual parts have to bemanufactured, handled and assembled, the inventive concept makes itpossible to establish—at each damper unit 40—both the damper functionand the horn spring function using one unitary damper unit 40 only,together with a simple bolt 120, compared to the prior art where anumber of different components must be handled and assembled, often fromdifferent sides of the horn plate 14.

The operation of the horn mechanism of the assembly 6 is as follows:When the horn mechanism is not activated by the driver, eachpre-compressed or biased horn spring part 94 presses against the flange56 of the slider 50, urging the slider 50 upwards in a direction awayfrom the base structure 12. The axial spring force is transferred viathe flange 56 to the damper element 70, and via the support ring 74 tothe horn plate 14. It will here be noted that the bolt 120 has multiplefunctions:

-   -   the bolt 120 provides the guide shaft 122 for the axial movement        of the slider 50 during horn activation;    -   the bolt head 126 defines an upper axial stop for the axial        movement of the damper unit 40, and    -   the bolt head 126 assists in locking the damper unit 40 in place        in relation to the horn plate 14 by pressing on the top of the        damper element 70.

In the illustrated embodiment, the distal end 71 of the damper element70 extends a short distance beyond the upper edge of the sleeve 20,whereby the upper stop position of the damper unit 40 is defined by asoft engagement between the end 71 of the damper element 70 and the bolthead 120.

Upon horn activation, when the driver presses the horn pad 8 on thesteering wheel 2, the horn plate 14 is pressed towards the basestructure 12. The force is transferred via the damper element 40 to theslider 50, which is thereby displaced along the guide shaft 122compressing the horn spring part 94 further in the axial direction untilthe distance D in FIG. 5 is reduced to zero and the horn switch 15, 30is closed. When the pressure on the horn pad 8 is released, the hornspring part 94 will return the horn plate 14 to its normal position,whereby the soft engagement between the elastomeric end portion 71 andthe bolt head 124 provides a “soft” stop.

The damper function of the assembly 6 is as follows: Steering wheelvibrations V (FIG. 7) occurring in the steering wheel 2 and the basestructure 12 are transferred via the bolts 120 and the sliders 50 to theelastomeric damper elements 70. The damper elements 70 transfer thesteering wheel vibrations V to the horn plate 14 via the sleeves 20,thereby causing the mass (represented by the weight of the horn plate,the airbag assembly and any other details supported by the horn plate14) to vibrate out of phase such that the vibrations V in the steeringwheel 2 are dynamically dampened. During the vibration dampening, theradial compression of the elastomeric material of the damper elements 70will vary. Thanks to the ribbed design of the damper elements 70, thecompressed elastomeric material may expand into the spaces 78 betweenthe ribs 77. This solution gives an advantageous more linear relationbetween the damper compression and the spring constant of the damperelement 70. In a non-ribbed, solid cylinder of elastomeric material, thematerial has no such “escape”, resulting in a more non-linear springconstant, making the dynamic dampening function less efficient becausematching the target frequency will be more difficult. A furtheradvantage obtained by the ribbed configuration is an increasedflexibility in the frequency tuning during design and manufacturing. Thedampening frequency of the assembly may be tuned by varying one or moreparameters such as the number of ribs 77, the circumferential, radial,and/or axial dimensions of the ribs 77 and the spaces 78 between theribs 77. Thus, one may use thicker or thinner ribs; longer or shorterribs in the axial direction; longer or shorter ribs in the radialdirection, etc. Also, the frequency interval within which the damperelement 70 is tunable may be expanded by using a ribbed configurationcompared to prior-art damper elements.

During the vibration damping operation, the horn plate 14 will thus becaused to move in directions perpendicular to the axis A, especially inrelation to the lower or proximal part 72 of the damper element 70supporting the horn plate 14 in the axial direction. Since the radiallymoving horn plate 14 at its rear side is in direct contact with thesurface of the lower part 72, such radial movements of the horn plate 14may give rise to unwanted frictional movements and silicone wear at theinterface between the bottom side of the horn plate 14 and the damperelement 70 at reference numeral 74 in FIG. 7. Also, this direct axialcontact between the lower part 72 of the damper element 70 and the rearside of the horn plate 14 may influence the damping function (tuning) ina negative way. This is the reason for providing the ring shaped groove76. Thereby, the support ring 74 will be more free to move in theleft-right direction in FIG. 7, together with a left-right movement ofthe horn plate 14 during damping, resulting in less frictional movementsbetween the horn plate 14 and the damper element 70, and also resultingin a “de-coupling” of the vibration dampening from the contact betweendamper element part 70 and the rear side of the horn plate 14.

2^(nd) Embodiment

FIGS. 11A and 11B illustrate a 2^(nd) embodiment of a damper unit 240.Same reference numerals are used as in the first embodiment above, butin a 200-series. Although the solution with the ring 74 and thering-shaped groove 76 as described in the preceding paragraph may beadvantageous, it will be noted that the added movability is obtained inthe vibration direction only. If for instance the vibrations V aredirected left-right in FIG. 7, then the parts of the support ring 74shown to the left and to the right in FIG. 7 would be free to move withthe horn plate 12 due to the groove 76. However, at differentcircumferential locations on the support ring 74 facing towards and awayfrom the reader in FIG. 7, such left-right movement will not be allowedby the groove 76.

In order to address this problem, the bottom part 271 of the damperelement 270 according to the 2^(nd) embodiment may be designed as shownin FIGS. 11A and 11B.The support ring 74 in the 1^(st) embodiment isdivided in the circumferential direction into a number of individualsupport studs 274 with spaces 279 there between in the circumferentialdirection. Compared to the ring design 74, the individual support studs274 will be more flexible in all radial directions. This design willallow the support studs 274, which are in engagement with the rear sideof the horn plate 14, to move together with the horn plate 14 duringvibration damping, both radially and circumferentially in relation tothe axis A without substantially affecting the vibration dampingoperation. This design allows the support studs 274 to better follow themovement of the horn plate 14. In order to obtain a uniform movabilityin all directions, the support studs 274 may preferably have a circularcross section, i.e. essentially same dimensions in all directionsperpendicular to the axis A.

3^(rd) Embodiment

FIGS. 12A and 12B illustrate a third embodiment of a spring unit 340 foruse in situations where different dampening properties are required indifferent directions. Same reference numerals are used as above, but ina 300-series. Support studs 374 and spaces 376 are arranged as in the2^(nd) embodiment. In the 3^(rd) embodiment, the elastomeric damperelement 370 of the spring unit 340 has a non-circular configuration,such as an oval or elliptic configuration. As shown in FIG. 12B, thenon-circular damper element 370 is received in a correspondingnon-circular opening 321 in the horn plate 14. By this no-circulardesign, the assembly may present different tuning frequencies in thevertical and the horizontal direction in FIG. 12B.

4^(th) Embodiment

FIGS. 15A to 15C illustrate a 4^(th) embodiment of a damper unit 440.The same reference numerals are used as above, but in a 400-series. Theslider 450 of the damper unit 440 is shown in FIGS. 13A to 13D. Thedamper element 470 of the damper unit 440 is shown in FIGS. 14A to 14D.Everything stated above for the previous embodiments regarding themanufacture, optional bonding, function, material, etc. applies to thisembodiment 440 also in all relevant parts.

Like in the 2^(nd) embodiment, the damper element 470 of the damper unit440 according to the 4^(th) embodiment is divided into a plurality ofaxially extending ribs 477, which are circumferentially distributedabout the axis A of the damper unit 440 and which define spaces 478there between. The operation and advantages of the ribs as describedabove will apply in all relevant aspect to this 4^(th) embodiment also.However, this 4^(th) embodiment of the damper unit 440 presents someadditional features.

In the 4^(th) embodiment, and as seen in the direction of the axis A,each rib 477 has proximal rib part 477 a forming the vibration dampingpart of the rib 477, and a distal rib part 477 b not primarily takingpart in the vibration damping operation (FIGS. 14A to 14C). The proximalrib part 477 a has an outer radial surface 475 extending in parallelwith the axis A. The radially outer surfaces 475 of the ribs 477together form the outer engagement surface of the damper element 470. Inthe final assembly, the proximal rib part 477 a will be held in aslightly compressed state in the radial direction as described above.The distal rib part 477 b has a radial extension 473 for lockingpurposes, similar to the radial extension 73 in the 1^(st) embodiment.The radial extension 473 presents a proximal inclined locking surface473 a and a distal inclined insertion surface 473 b. Furthermore, in theillustrated 4^(th) embodiment, there may be a gap 473 c in the radialdirection between the distal rib part 477 b and the tubular element 458of the slider 450. In other embodiments, this radial gap 473 c may bedispensed with.

The horn spring element 490 of the damper unit 440 is arranged on theopposite side of the slider flange 456 on the lower tubular part 460 ofthe slider 450. What stated above in the 1^(st) embodiment regarding thestructure, the manufacturing, alternatives, and the operation of thehorn spring element 90 applies to the horn spring element 490 in this4^(th) embodiment in all relevant aspects. In the illustratedembodiment, the horn spring element 490 is molded in one piece with theelastomeric damper element 470 on the slider 450 as in the 1^(st)embodiment, with elastomeric locking elements 100 extending throughopenings 462 in the slider flange 456. In this embodiment, a portion 101of the elastomeric material also extends radially outside the outer rimof the slider flange 456. In alternative embodiments, the damper element470 and the horn spring element 490 may be held together in one piece bylocking elements 100 only or by the portion 101 only.

In the 4^(th) embodiment, and as shown in FIGS. 14A to 14C and FIGS. 15Ato 15D, the elastomeric damper element 470 is provided with a first setof individual support studs 474 a and a second set of individual supportstuds 474 b. The support studs 474 a in the first set are slightlyhigher in the axial direction by an amount Δ compared to the supportstuds 474 b in the second set. As a non-limiting example, the value of Δmay be in the order of one or a few millimeters. In the illustratedembodiment, the support studs 474 a, 474 b of the two sets areinterlaced in the circumferential direction. The support studs 474 a,474 b are spaced from each other in the circumferential direction andspaced from the slider in the radial direction. In preferred embodimentas shown, the support studs 474 b in the second set are larger than thesupport studs 474 a in the first set in that they have a largercross-section perpendicular to the axis A. In the following, thesedifferent studs will be referred to as the smaller support studs 474 aand the larger support studs 474 b. In the illustrated embodiment, thesmaller support studs 474 a have a circular cross-section and the largersupport studs 474 b have an elongate cross-section. The design and shapeof the support studs 474 a and 474 b may vary from the example. Thesmaller support studs 474 a have essentially the same function as thesupport studs 274 in the 2^(nd) embodiment, i.e. they ensure that thecontact or interface between the supporting studs and the rear side ofthe horn plate 14 is flexible in the radial plane in order not tointerfere with the vibration damping. The function of the larger studs474 b will be explained below.

FIGS. 16A to 16E illustrate a method for assembling a vibration damperassembly 6 (FIG. 16F) comprising three damper units 440 according to the4^(th) embodiment. FIG. 16A illustrates a damper unit 440 to be insertedfrom below into one of three openings in a horn plate 14. As in theprevious embodiments, the slider 450 and the elastomeric damper element470 of each damper unit 440 are inserted together and from one side onlyof the horn plate 14. In the illustrated embodiment, each opening of thehorn plate 14 is provided with a sleeve 20. The sleeve is preferablymade of a relatively rigid material, such as a rigid plastic materialmolded to the horn plate. One function of the sleeve 20 is to provide anaxially extended engagement surface for the damper element 470. Anotherfunction of the sleeve 20 is to protect the elastomeric damper element470 from damage during assembly and during operation.

As shown in FIG. 16B, the inner radial dimension of the sleeve isselected such that the distal inclined insertion surfaces 473 b of theribs 477 will guide the damper unit 440 into the opening and also assistin pressing or forcing the elastomeric damper element 470 through theopening.

FIG. 16C illustrates how the radial extensions 473 of the ribs 477 willbe pressed radially inwards as the damper unit 440 is moved through theopening of the sleeve 20. This radial movement may be possible due to aninwardly radial bending of the distal rib parts 477 b and/or due to aradial compression of the extensions 473.

FIG. 16D illustrates the final mounted position of the damper unit 440in relation to the horn plate 14. The final position is defined by aninsertion position where the smaller support studs 474 a are brought toengagement with the underside of the sleeve 20. The engagement may alsobe directly with the rear side of the horn plate 14. When the damperunit 440 has been fully inserted to its final position, the extensions473 of the ribs 477 will snap radially outwards as shown by arrows inFIG. 16D. The proximal inclined locking surface 473 b of each rib 477will now be in a locking engagement with the upper side of a radialextension of the sleeve 20 to lock the damper unit 440 in place. Thedamper unit 440 is now held axially in its final position by theelastomeric damper element 470, namely by the smaller support studs 474a on the one hand, and the radial extensions 473 on the other hand. Thelarger support studs 474 b are not in use at this stage.

As described above for the 1^(st) embodiment, during insertion of thedamper element 470, the radially outer engagement surfaces 475 of theproximal rib parts 477 a are brought into engagement with the innerengagement surface 21 of the corresponding sleeve 20, such that steeringwheel vibrations V may be transferred from the damper element 470 to thehorn plate 14. In order to achieve a proper vibration damping effect,the radial dimensions are preferably selected such that the damperelement 470 is somewhat radially pre-compressed between the slider 450and the inner engagement surface 21 of the sleeve 20 as a result of theinsertion.

When the damper elements 470 have been correctly positioned in the hornplate 14, a bolt 120 may be inserted into the bore 454 of each slider450 as shown in FIG. 16E. Each bolt 120 has a bolt head 126, acylindrical guide shaft 122 and a threaded end 124. The tubular part 452of the slider 450 may slide along the guide shaft 122. The bolts 120 aresecured in bolt holes of the extensions 13 of the base structure 12.

During the final fastening of each bolt 120 (FIG. 16F), apre-compression of the corresponding horn spring part 494 is obtained.As a non-limiting example, a horn spring part 494 may be pre-compressedfrom 10 mm to 7 mm during assembly and then further compressed one or afew millimeters upon horn activation. In the final assembly 6, thedistal end 495 of each horn spring part 494 engages the associated hornspring support surface 26 of the bracket 22.

As illustrated in the enlarged-scale view in FIG. 16F, during the finalfastening of each bolt 120, the bolt head 126 may engage and axiallycompress the ribs 477 until the distal ends of the ribs 477 are in levelwith the distal end of the slider 450. As illustrated with arrows inFIG. 16F, this final compression will lock the radial extensions 473 orthe ribs 477 tighter to the sleeve 20 and thereby fix the damper unit440 even more securely in the axial direction in relation to the hornplate 14. In other embodiments, such a final compression may bedispensed with.

The operation of the larger/stiffer support studs 474 b will now bedescribed with reference to FIGS. 17A to 17C. Before the driveractivates the horn (FIG. 17A), the rear side of each sleeve 20 is incontact with the smaller support studs 474 a only, with an axial gap Δbeing present between the rear side of the sleeve 20 and the largersupport studs 474 b.

FIG. 17B illustrates an initial stage of horn activation, where thedriver has just initiated the horn activation by pressing the hornactivation pad 8. The horn plate 14 has now moved axially a distance Δ.The small support studs 474 a have been axially compressed due to theirrelatively small cross-sectional dimension. Therefore, the compressionof the horn spring 494 has not yet started. When the small support studs474 a have been axially compressed to a degree where they have the sameaxial height as the larger support studs 474 b, the rear side of thesleeve 20 will have contact with both the smaller support studs 474 aand the larger support studs 474 b, as shown in the enlarged scale viewin FIG. 17B. The distance Δ is now eliminated. Accordingly, selectingsmall dimensions for the first set of support studs 474 a has theadvantage of both ensuring a flexible interface and ensuring an axialcompression upon horn activation.

FIG. 17C illustrates the subsequent stage of horn activation. When thedistance Δ towards the larger support studs 474 b has been eliminated,the total axial stiffness of all the support studs 474 a and 474 b incombination will now be sufficient for the horn spring part 494 to becompressed when the driver presses the horn activation pad 8. Forillustration purposes only, FIG. 17C shows the movement of the hornplate 14 and the compression of the horn spring in a very exaggeratedscale. In reality, this movement may be in the order of one or fewmillimeters only.

A specific advantage obtained by this design including support studs 474a and 474 b with different heights, and optionally with different axialstiffness, is that two advantageous properties may be obtained at thesame time, one relating to the vibration damping and one relating tohorn activation. With regard to vibration damping, a radially flexibleinterface is preferred between the elastomeric material and the rearside of the sleeve 20 or horn plate 14. With regard to horn activation,an axially stiff interface is preferred at the same location in order toinitiate the horn spring compression as soon as possible when the driverpresses the pad 8. This “dilemma” is solved by providing the differentsupport studs 474 a and 474 b, creating a “dynamic” support interface.

On the one hand, when no horn activation is present, the rear side ofthe horn plate 14 is supported by the relatively flexible smallersupport studs 474 a only. This has the advantage that the interfacebetween the elastomeric material and the rear side of the horn plate 14does not interfere with the vibration damping function. The largersupport studs 474 b are inactive when no horn activation is present. Onthe other hand, when horn activation is initiated, it is preferred thata fully developed horn spring force is obtained as soon as possible.Thanks to the presence of the larger and relatively stiff support studs474 b, and the relatively low axial stiffness of the smaller supportstuds 474 a, the distance Δ can be very quickly eliminated when hornactivation is initiated by axially compression of the smaller supportstuds 474 a, such that the desired axially stiff interface can beestablished despite that the interface is flexible during normalvibration damping.

Alternatives

The embodiments described above and as shown in the figures may bevaried in many ways.

In the illustrated embodiments, the guide shaft is part of a boltscrewed into the vibrating base structure. The guide shaft may beimplemented differently, for instance by a guide shaft made in one piecewith the vibrating structure and optionally with a free threaded end forsecuring the assembly by a nut. Also, it may in some embodiments bepossible to have the bolt oriented the opposite direction, i.e. to bescrewed into the horn plate instead.

In alternative embodiments, the sleeves 20 of the horn plate aredispensed with and the damper elements are connected to the horn plate14 in a different way, optionally in direct contact with the horn plate14.

The second tubular portion of the slider may in other embodiments extendfurther into the horn spring part, but preferably not all the way inorder to allow movement of the slider upon horn activation. In someembodiment, the second tubular portion is dispensed with and the hornspring element is attached to the slider in some other way, such as tothe flange only.

In some embodiments, the outer engagement surface of the damper elementmay extend substantially 360 degrees circumferentially around the axisof the damper unit, such that vibrations may be transferred inessentially all radial directions. Such embodiments are considered toinclude ribbed designs also, where the outer engagement surface is notcontinuous in the circumferential direction.

In other embodiments, the outer engagement surface of the damper elementmay be present in some directions only if the damper unit is configuredto transfer vibrations in some specific directions only. This may beimplemented in various ways, such as by arranging inner protruding partsin the mounting opening of the horn plate defining circumferentiallylimited inner engagement surfaces, such as inner protruding parts on thesleeves. This may also be implemented by designing the elastomericdamper element with engagement surfaces in some directions only. In suchembodiments where one single damper unit is arranged to transfervibrations in specific directions only, the complete assembly maycomprise a number of damper units arranged to handle vibrations indifferent directions. As an example, One or more damper units may beconfigured to dampen vibrations in a vertical direction and one or moreother damper units may be configured to dampen vibrations in ahorizontal direction.

In alternative embodiments, the slider and the corresponding channels orbores of the elastomeric elements may have a non-circular cross-section,for instance if different damping properties in different directions aredesired and the damper unit therefore has to be oriented in a specificway on the guide shaft.

1.-16. (canceled)
 17. A damper unit for use in a vibration-reducingassembly for a steering wheel, said damper unit comprising: a sliderhaving a central bore extending along an axis, said slider beingconfigured, upon horn activation on the steering wheel, to slide in adirection of said axis on a guide shaft received in said central bore; adamper element which is made from an elastomeric material and is moldedon a first part of the slider; and a molded horn spring element which ismade from an elastomeric material and comprises a horn spring part andan attachment part molded in one piece and molded in one piece with thedamper element, wherein the attachment part of the horn spring elementis molded on a second part of the slider, and wherein the horn springpart is configured to exert a force on the slider in the direction ofthe axis.
 18. The damper unit as claimed in claim 17, wherein theattachment part of the horn spring element is mechanically bonded to theslider.
 19. The damper unit as claimed in claim 18, wherein theattachment part of the horn spring element is mechanically bonded to theslider by one or more molded locking elements, which are molded in onepiece with the horn spring element and the damper element, and which arein mechanical locking engagement with associated one or more lockingopenings in the slider.
 20. The damper unit as claimed in claim 19,wherein the slider comprises: a tubular element extending along saidaxis and including said central bore; and a flange extending radiallyoutwards from the tubular element and including said locking openings inthe form of through-holes; wherein the damper element and the hornspring element are located on opposite axial sides of the flange; andwherein the damper element, the horn spring element and the lockingelements are molded in one piece such that the damper element and thehorn spring element are mechanically bonded to the slider via thelocking elements extending through the locking openings of the flange.21. The damper unit as claimed in claim 17, wherein the horn spring partof the horn spring element extends at least in part axially beyond theslider.
 22. The damper unit as claimed in claim 17, wherein the hornspring part is at least partly bellow-shaped.
 23. The damper unit asclaimed in claim 17, wherein the attachment part of the horn springelement is chemically bonded to the slider.
 24. The damper unit asclaimed in claim 17, wherein the damper element is at least one ofmechanically or chemically bonded to the slider.
 25. Avibration-reducing assembly for dampening vibrations in a steeringwheel, comprising: a base structure which is fixed to the steering wheeland presents vibrations to be dampened; a guide shaft fixed to the basestructure; a damper unit as claimed in claim 17, wherein the guide shaftis slidably received in the central bore of the slider, and wherein thehorn spring part of the damper unit is configured, upon horn activationon the steering wheel, to be compressed in response to the slider movingalong the axis of the damper unit towards the base structure; and a masswhich is supported by the base structure via the damper element of thedamper unit for allowing movement of the mass perpendicular to saidaxis; wherein the damper element of the damper unit is configured totransfer vibrations, directed perpendicular to said axis, from thesteering wheel to the mass; and wherein the damper element and the massare configured to operate as a spring-mass system forming afrequency-tuned dynamic damper for dampening said vibrations in the basestructure and the steering wheel.
 26. The vibration-reducing assembly asclaimed in claim 25, wherein a weight of the mass comprises at least aweight of a horn plate and a weight of an airbag assembly supported bythe horn plate; and wherein the horn plate is supported by theelastomeric damper element of the damper unit.
 27. Thevibration-reducing assembly as claimed in claim 26, wherein the damperelement of the damper unit is received in a mounting opening of the hornplate, and wherein the damper element includes an outer engagementsurface, which is in engagement with an inner engagement surface of amounting opening of the horn plate for transferring said vibrations. 28.The vibration-reducing assembly as claimed in claim 27, wherein thedamper element of the damper unit includes a plurality of mutuallyspaced ribs, said ribs together forming the outer engagement surface ofthe damper element.
 29. The vibration-reducing assembly as claimed inclaim 25, wherein the guide shaft is part of a threaded bolt, andwherein a bolt head of the bolt is configured to act as a stop forlimiting movement of the slider in one direction.
 30. A method formanufacturing a damper unit as claimed in claim 17, the methodcomprising: providing the slider having the central bore extending alongthe axis of the damper unit; providing the damper element on the firstpart of the slider; providing the horn spring element comprising thehorn spring part and the attachment part molded in one piece, whereinthe attachment part is molded on the second part of the slider; whereinproviding the damper element and providing the horn spring elementcomprise molding the damper element and the horn spring element in onepiece on the slider from the elastomeric material.
 31. The method formanufacturing as claimed in claim 30, wherein the slider comprises atubular element extending along said axis, and a flange extendingradially outwards from the tubular element and including one or morelocking openings in the form of through-holes; and wherein molding thedamper element and the horn spring element in one piece comprisesmolding the damper element and the horn spring element on axiallyopposite sides of the flange and with one or more locking elements, saidlocking elements extending through said locking openings, therebymechanically bonding the damper element and the horn spring element tothe slider.
 32. The damper unit as claimed in claim 18, wherein the hornspring part of the horn spring element extends at least in part axiallybeyond the slider.
 33. The damper unit as claimed in claim 19, whereinthe horn spring part of the horn spring element extends at least in partaxially beyond the slider.
 34. The damper unit as claimed in claim 20,wherein the horn spring part of the horn spring element extends at leastin part axially beyond the slider.
 35. The damper unit as claimed inclaim 18, wherein the horn spring part is at least partly bellow-shaped.36. The damper unit as claimed in claim 19, wherein the horn spring partis at least partly bellow-shaped.